The present invention is generally directed to an accessory for an internal combustion engine, and more particularly to an assembly for mounting on an exhaust manifold of an engine to induct air into the exhaust manifold.
During the operation of an internal combustion engine, gases resulting from an explosion in a cylinder of the engine are expelled from the cylinder in an initial high pressure pulse or wave. It has been determined that the initial high pressure wave or pulse has a relatively long duration, and is followed by a series of alternating low and high pressure pulses of shorter duration. A series of alternating high and low pressure waves is formed in the exhaust manifold each time an exhaust valve for any one of a plurality of engine cylinders is opened. During the high pressure pulses, combustion products or exhaust gases are expelled from the cylinders of the engine. However, during the low pressure pulses, the mainly noncombustible exhaust gases are drawn back into the cylinders. These exhaust gases are often retained in the cylinder when the exhaust valve closes and the gases substantially dilute the air-fuel mixture for the next cycle of operation. This dilution of the air-fuel mixture with largely noncombustible exhaust gases significantly retards combustion within the cylinder on the succeeding power stroke.
The quantity of largely noncombustible exhaust gases which are drawn into the cylinder during a low pressure pulse or wave can be substantially reduced by inducting air into the exhaust manifold during the low pressure pulse. The induced air dilutes the noncombustible exhaust gases retained in the cylinders, and further serves to displace a volume of the noncombustible exhaust gases. As a result, the induced air increases the power and efficiency of the engine by reducing carbon deposits and promoting more complete fuel combustion. Experience has even shown that the inducted air actually cleans up the carbon in an internal combustion engine.
Devices to promote the induction of air into an exhaust manifold as described above are known in the art. One such device, for example, is shown and described in Flint U.S. Pat. No. 3,455,106 which issued on July 15, 1969. The device there shown and described includes a stem section having a longitudinal passageway therein. One end of the stem section is adapted to be connected to the exhaust manifold and the other end of the stem section supports a check valve. The check valve includes a plurality of valve members which float with respect to a valve seat for opening and closing the valve during the alternating high and low pressure waves. The floating action of the valve members was found to provide a highly responsive and sensitive check valve necessary for proper operation of such a device due to the fact that the positive and negative pressure pulse waves set up in the exhaust system of an engine occur in rapid succession. For example, a four-cylinder four-stroke engine, which is operating at 1800 rpm, has fifteen openings and closings per second of the exhaust valve associated with each cylinder. Therefore, the four-cylinder engine sets up sixty series of high and low pressure pulses in the exhaust manifold per second. Since each series of pulses includes a plurality of high and low pressure peaks and valleys, the check valve assembly must operate far in excess of sixty times a second when the engine is operating at 1800 rpm.
While the aforementioned check valve disclosed in U.S. Pat. No. 3,455,106 has made significant advances in the art, the present invention provides further improvements. As will be fully described hereinafter, the manifold device of the present invention includes a new and improved check valve construction comprising substantially fewer moving parts than the previously described check valve which are supported by a spring for positively positioning the same within the valve in the absence of manifold pressure. However, in the presence of manifold pressure, and specifically the pressure waves established during the operation of the engine, the spring supporting the valve members allows the valve members to float, between an open and closed position to promote rapid opening and closing of the valve. Further, the device of the present invention includes a pump arrangement which is operative responsive to the exhaust pressure waves for pumping and directing air into the check valve during its operation. As a result, because the check valve of the present invention includes fewer moving parts which are positively positioned by the aforementioned spring, the device of the present invention experiences reduced wear during operation and is substantially more responsive to the alternating positive and negative exhaust pressures for inducting an increased volume of air into the exhaust manifold than heretofore possible. Furthermore, by virtue of the pump structure to be described hereinafter, a further increase in inducted air is promoted.
It is therefore a general object of the present invention to provide a new and improved assembly for mounting on an exhaust manifold of an engine to induct air into the exhaust manifold.
It is a further object of the present invention to provide such an assembly which includes a new and improved check valve arrangement which includes substantially fewer moving parts than check valves of the prior art, and a means for positively positioning the valve members prior to and during the operation of the check valve.
It is a still further object of the present invention to provide such an assembly which further includes a pump for forcing and directing air into the check valve during its operation, to thereby provide an increased volume of inducted air into the exhaust manifold.
The invention therefore provides an assembly for mounting on an exhaust manifold of an engine to induct air into the exhaust manifold. The assembly includes a stem section adapted to be connected to the exhaust manifold which stem section includes a continuous passage. A hollow cylindrical member is connected to the stem section and defines a valve chamber communicating with the stem section passage. Within the valve chamber there is disposed a valve means which includes a coiled spring extending into the valve chamber, an annular valve seat tightly received within the cylindrical member and having an annular valve seat surface facing the coiled spring, and valve member means including a solid disc arranged to be forced against the annular valve surface by the coiled spring in the absence of manifold pressure, and an apertured disc between the solid disc and the coiled spring for promoting movement of the solid disc into sealing engagement with and away from the annular valve seat surface in response to cyclically occurring positive and negative manifold pressures respectively. The discs are smaller in diameter dimension than the cylindrical member. A housing surrounds the valve chamber which is vented to external atmosphere for providing a volume of air in communication with the valve means. An air pump, including a flutter disc, is disposed within the housing across the valve chamber and is arranged for reciprocating movement responsive to variations in manifold pressure. As a result, when the manifold pressure is positive, the solid disc sealingly engages the annular valve seat surface for closing the valve and when the manifold pressure is negative, the solid disc is displaced from the annular valve seat surface for inducting air into the exhaust manifold while the flutter disk is resiliently displaced towards the valve chamber to draw a quantity of air into the housing for induction into the exhaust manifold during the next cycle of negative manifold pressure.